All problems
866 problems across 7 tracks. Filter by what you want to practise today.
866 problems
- +10 XPeasySoftmax with TemperatureAI Engineering & LLMs · #llm #sampling #numerics
- +25 XPmediumScaled Dot-Product AttentionAI Engineering & LLMs · #transformers #attention #numpy
- +25 XPmediumTop-k & Top-p (Nucleus) FilteringAI Engineering & LLMs · #llm #sampling #decoding
- +10 XPeasyEmbedding Retrieval with Cosine SimilarityAI Engineering & LLMs · #rag #embeddings #vector-search
- +10 XPeasyChunking Documents for RAGAI Engineering & LLMs · #rag #preprocessing
- +25 XPmediumByte-Pair Encoding: One Merge StepAI Engineering & LLMs · #tokenization #llm
- +10 XPeasyLoRA: Count Trainable ParametersAI Engineering & LLMs · #fine-tuning #peft #lora
- +10 XPeasyPerplexity from Token Log-ProbsAI Engineering & LLMs · #evaluation #llm
- +25 XPmediumEvaluating an LLM-as-Judge (Cohen's κ)AI Engineering & LLMs · #evaluation #llm-as-judge #statistics
- +25 XPmediumKV-Cache Memory BudgetAI Engineering & LLMs · #inference #systems #gpu
- +10 XPeasyHybrid Search with Reciprocal Rank FusionAI Engineering & LLMs · #rag #retrieval #ranking
- +10 XPeasyRepetition PenaltyAI Engineering & LLMs · #llm #sampling #decoding
- +25 XPmediumSpeculative Decoding: Verify the DraftAI Engineering & LLMs · #llm #inference #decoding
- +50 XPhardRotary Position Embeddings (RoPE)AI Engineering & LLMs · #transformers #attention #numpy
- +25 XPmediumBM25 Keyword SearchAI Engineering & LLMs · #rag #retrieval #search
- +10 XPeasyFit Chat History in the Context WindowAI Engineering & LLMs · #llm #context-window #chatbots
- +25 XPmediumINT8 Weight QuantizationAI Engineering & LLMs · #inference #quantization #numpy
- +25 XPmediumMixture-of-Experts Top-k RoutingAI Engineering & LLMs · #transformers #moe #numpy
- +50 XPhardBeam Search DecodingAI Engineering & LLMs · #llm #decoding #search
- +10 XPeasyKL DivergenceAI Engineering & LLMs · #probability #llm #numpy
- +25 XPmediumKnowledge Distillation LossAI Engineering & LLMs · #distillation #training #numpy
- +50 XPhardDirect Preference Optimization (DPO) LossAI Engineering & LLMs · #alignment #rlhf #llm
- +10 XPeasySelf-Consistency: Majority Vote over SamplesAI Engineering & LLMs · #llm #reasoning #prompting
- +10 XPeasySentence Embeddings: Masked Mean PoolingAI Engineering & LLMs · #embeddings #rag #numpy
- +25 XPmediumMulti-Head Attention: Split and Merge HeadsAI Engineering & LLMs · #transformers #attention #numpy
- +25 XPmediumExtract JSON from an LLM ReplyAI Engineering & LLMs · #llm #structured-output #parsing
- +10 XPeasyLLM API Cost EstimatorAI Engineering & LLMs · #llm #apis #cost
- +10 XPeasyPrompt Templates with ValidationAI Engineering & LLMs · #llm #prompting #strings
- +25 XPmediumSliding-Window Attention MaskAI Engineering & LLMs · #transformers #attention #long-context
- +25 XPmediumGrouped-Query Attention (GQA)AI Engineering & LLMs · #transformers #attention #inference
- +25 XPmediumBuild a Mini Agent LoopAI Engineering & LLMs · #agents #tool-use #llm
- +50 XPhardTiled Attention with Online SoftmaxAI Engineering & LLMs · #attention #inference #flash-attention
- +50 XPhardTrain a BPE TokenizerAI Engineering & LLMs · #tokenization #llm #strings
- +25 XPmediumRAG Retrieval Metrics: Recall@k, MRR, nDCGAI Engineering & LLMs · #rag #evaluation #retrieval
- +50 XPhardSpeculative Sampling (Probabilistic)AI Engineering & LLMs · #inference #decoding #probability
- +25 XPmediumRedact PII Before Sending to an LLMAI Engineering & LLMs · #guardrails #privacy #regex
- +25 XPmediumSemantic Cache for LLM ResponsesAI Engineering & LLMs · #caching #embeddings #cost
- +25 XPmediumParse a Streaming LLM Response (SSE)AI Engineering & LLMs · #streaming #apis #parsing
- +50 XPhardInfoNCE Contrastive LossAI Engineering & LLMs · #embeddings #training #clip
- +25 XPmediumDiverse Retrieval with Maximal Marginal RelevanceAI Engineering & LLMs · #rag #retrieval #ranking
- +50 XPhardNear-Duplicate Detection with MinHashAI Engineering & LLMs · #dedup #hashing #data-pipelines
- +25 XPmediumMin-p SamplingAI Engineering & LLMs · #sampling #decoding #llm
- +25 XPmediumStop Sequences in a Token StreamAI Engineering & LLMs · #streaming #decoding #strings
- +25 XPmediumpass@k for Code GenerationAI Engineering & LLMs · #evaluation #code-generation #probability
- +10 XPeasyQA Evaluation: Exact Match and Token F1AI Engineering & LLMs · #evaluation #nlp #rag
- +25 XPmediumBLEU Score from ScratchAI Engineering & LLMs · #evaluation #translation #nlp
- +25 XPmediumROUGE-L for SummariesAI Engineering & LLMs · #evaluation #summarization #nlp
- +10 XPeasyElo Ratings for a Model ArenaAI Engineering & LLMs · #evaluation #ranking #llm
- +25 XPmediumReward Model Training Loss (Bradley–Terry)AI Engineering & LLMs · #rlhf #alignment #training
- +50 XPhardPPO Clipped Policy ObjectiveAI Engineering & LLMs · #rlhf #reinforcement-learning #training
- +25 XPmediumGRPO Group-Relative AdvantagesAI Engineering & LLMs · #rlhf #reasoning #reinforcement-learning
- +25 XPmediumBinary Embeddings and Hamming SearchAI Engineering & LLMs · #embeddings #vector-search #quantization
- +25 XPmediumParse a ReAct Agent StepAI Engineering & LLMs · #agents #parsing #prompting
- +10 XPeasyLogit Bias and Banned TokensAI Engineering & LLMs · #decoding #llm #control
- +25 XPmediumPack Retrieved Chunks into a Token BudgetAI Engineering & LLMs · #rag #context-window #greedy
- +25 XPmediumCheck That Citations Are GroundedAI Engineering & LLMs · #rag #evaluation #hallucination
- +25 XPmediumRecursive Character Text SplitterAI Engineering & LLMs · #rag #chunking #strings
- +10 XPeasyHybrid Search: Normalise and Blend ScoresAI Engineering & LLMs · #rag #retrieval #ranking
- +25 XPmediumFlag Likely Prompt InjectionsAI Engineering & LLMs · #security #guardrails #llm
- +50 XPhardConstrained Decoding with a Token TrieAI Engineering & LLMs · #structured-output #decoding #tries
- +50 XPhardPaged KV-Cache Block AllocatorAI Engineering & LLMs · #inference #memory #systems
- +50 XPhardSimulate Continuous BatchingAI Engineering & LLMs · #inference #scheduling #systems
- +10 XPeasyLLM Serving Throughput CalculatorAI Engineering & LLMs · #inference #capacity-planning
- +10 XPeasyMerge LoRA Adapters into Base WeightsAI Engineering & LLMs · #fine-tuning #lora #inference
- +25 XPmediumGroup-Wise INT4 QuantisationAI Engineering & LLMs · #quantization #inference #numpy
- +25 XPmediumStreaming KV Cache with Attention SinksAI Engineering & LLMs · #inference #long-context #kv-cache
- +25 XPmediumThe Full Sampling PipelineAI Engineering & LLMs · #sampling #decoding #llm
- +50 XPhardIVF Vector Index (Inverted File)AI Engineering & LLMs · #vector-search #clustering #ann
- +50 XPhardProduct Quantisation for Vector CompressionAI Engineering & LLMs · #vector-search #quantization #compression
- +25 XPmediumGPT-2 Style Pre-tokenisationAI Engineering & LLMs · #tokenization #regex #llm
- +25 XPmediumRepair Almost-Valid JSONAI Engineering & LLMs · #structured-output #parsing #llm
- +25 XPmediumGenerate a Tool Schema from a Python FunctionAI Engineering & LLMs · #agents #tool-use #introspection
- +10 XPeasyCost-Aware Model RouterAI Engineering & LLMs · #llm #routing #cost
- +10 XPeasyPrompt Cache KeysAI Engineering & LLMs · #caching #llm #hashing
- +25 XPmediumSentence-Aware Chunking with OverlapAI Engineering & LLMs · #rag #chunking #nlp
- +25 XPmediumEvaluate Structured Extraction Field by FieldAI Engineering & LLMs · #evaluation #structured-output #extraction
- +25 XPmediumMeasure LLM-Judge Position BiasAI Engineering & LLMs · #evaluation #llm-as-judge #bias
- +25 XPmediumDetect Embedding Drift in ProductionAI Engineering & LLMs · #monitoring #embeddings #mlops
- +10 XPeasyDetect an Agent Stuck in a LoopAI Engineering & LLMs · #agents #reliability #monitoring
- +25 XPmediumBatch Texts for an Embeddings APIAI Engineering & LLMs · #apis #batching #rag
- +10 XPeasyExtract the Final Answer from Chain-of-ThoughtAI Engineering & LLMs · #evaluation #reasoning #parsing
- +25 XPmediumChoose Few-Shot Examples by Similarity and DiversityAI Engineering & LLMs · #prompting #retrieval #in-context-learning
- +25 XPmediumBeam Search Scoring with Length PenaltyAI Engineering & LLMs · #decoding #beam-search #nlp
- +50 XPhardDetect an LLM Text WatermarkAI Engineering & LLMs · #safety #watermarking #statistics
- +25 XPmediumCheck a Benchmark for Training-Data ContaminationAI Engineering & LLMs · #evaluation #data #n-grams
- +50 XPhardMoE Load-Balancing Auxiliary LossAI Engineering & LLMs · #moe #transformers #training
- +10 XPeasyTraining Compute and Chinchilla ScalingAI Engineering & LLMs · #scaling-laws #training #capacity-planning
- +25 XPmediumStream Tokens Without Breaking CharactersAI Engineering & LLMs · #streaming #tokenizers #unicode
- +10 XPeasyTwo-Stage Retrieval with a RerankerAI Engineering & LLMs · #rag #reranking #retrieval
- +10 XPeasyAggregate an Eval Suite with Error BarsAI Engineering & LLMs · #evaluation #statistics #benchmarks
- +25 XPmediumValidate and Dispatch Tool CallsAI Engineering & LLMs · #agents #tool-use #validation
- +25 XPmediumConversation Memory with Rolling SummariesAI Engineering & LLMs · #memory #context-management #agents
- +10 XPeasyMeasure Over- and Under-RefusalAI Engineering & LLMs · #safety #evaluation #classification
- +25 XPmediumCalibrate Confidence with Temperature ScalingAI Engineering & LLMs · #calibration #evaluation #classification
- +25 XPmediumSchedule Requests Under RPM and TPM LimitsAI Engineering & LLMs · #apis #rate-limiting #scheduling
- +50 XPhardExtend Context with RoPE ScalingAI Engineering & LLMs · #positional-encoding #long-context #transformers
- +10 XPeasyReorder Context for Long-Context ModelsAI Engineering & LLMs · #rag #long-context #prompting
- +25 XPmediumPrompt Lookup DecodingAI Engineering & LLMs · #inference #speculative-decoding #latency
- +50 XPhardPrefix Caching with a Radix TreeAI Engineering & LLMs · #inference #kv-cache #tries
- +10 XPeasyRender and Parse a Chat TemplateAI Engineering & LLMs · #prompting #tokenizers #chat
- +25 XPmediumEncode Text with Learned BPE MergesAI Engineering & LLMs · #tokenizers #bpe #nlp
- +50 XPhardUnigram Tokenization with ViterbiAI Engineering & LLMs · #tokenizers #dynamic-programming #sentencepiece
- +10 XPeasyRoute Queries by Embedding CentroidsAI Engineering & LLMs · #routing #embeddings #classification
- +10 XPeasySmall-to-Big: Parent Document RetrievalAI Engineering & LLMs · #rag #retrieval #chunking
- +25 XPmediumLate Interaction Scoring (ColBERT MaxSim)AI Engineering & LLMs · #retrieval #embeddings #rag
- +25 XPmediumTruncate Matryoshka EmbeddingsAI Engineering & LLMs · #embeddings #retrieval #efficiency
- +25 XPmediumReference-Free Preference Losses: IPO and SimPOAI Engineering & LLMs · #alignment #preference-learning #rlhf
- +50 XPhardHeavy-Hitter KV Cache Eviction (H2O)AI Engineering & LLMs · #inference #kv-cache #attention
- +25 XPmediumIs Model B Really Better? (McNemar's Test)AI Engineering & LLMs · #evaluation #statistics #hypothesis-testing
- +25 XPmediumGuardrails for LLM-Generated SQLAI Engineering & LLMs · #safety #text-to-sql #parsing
- +10 XPeasyBest-of-N Sampling with a Reward ModelAI Engineering & LLMs · #alignment #inference #sampling
- +25 XPmediumTree Attention for Speculative DraftsAI Engineering & LLMs · #inference #speculative-decoding #attention
- +25 XPmediumFit Bradley–Terry Ratings from Pairwise VotesAI Engineering & LLMs · #evaluation #rankings #statistics
- +10 XPeasyRun Dependent Tool Calls in Parallel WavesAI Engineering & LLMs · #agents #scheduling #graphs
- +25 XPmediumPlan a Map-Reduce SummarisationAI Engineering & LLMs · #long-context #summarization #planning
- +10 XPeasyCompress Prompts by Self-InformationAI Engineering & LLMs · #prompting #cost #long-context
- +25 XPmediumAbstain When Unsure: Risk–Coverage CurvesAI Engineering & LLMs · #evaluation #uncertainty #calibration
- +50 XPhardParallel Jacobi DecodingAI Engineering & LLMs · #inference #decoding #parallelism
- +50 XPhardActivation-Aware Weight Quantisation (AWQ)AI Engineering & LLMs · #quantization #inference #llms
- +10 XPeasyCompare KV Cache Layouts: MHA, GQA, MQA and MLAAI Engineering & LLMs · #kv-cache #inference #capacity-planning
- +10 XPeasySemantic Deduplication of a DatasetAI Engineering & LLMs · #data #embeddings #clustering
- +50 XPhardParse Partial JSON While StreamingAI Engineering & LLMs · #streaming #parsing #structured-output
- +10 XPeasyScore an Agent's Tool-Call TrajectoryAI Engineering & LLMs · #agents #evaluation #tool-use
- +10 XPeasyHighlight Low-Confidence SpansAI Engineering & LLMs · #uncertainty #logprobs #ux
- +10 XPeasyFaithfulness from a Claim–Source Support MatrixAI Engineering & LLMs · #rag #evaluation #hallucination
- +10 XPeasyTokenizer Fertility Across LanguagesAI Engineering & LLMs · #tokenizers #multilingual #cost
- +25 XPmediumScalar Quantisation of EmbeddingsAI Engineering & LLMs · #embeddings #quantization #vector-search
- +50 XPhardSearch an HNSW GraphAI Engineering & LLMs · #vector-search #graphs #approximate-nearest-neighbours
- +25 XPmediumExpected Speedup of Speculative DecodingAI Engineering & LLMs · #inference #speculative-decoding #performance
- +10 XPeasyLogit Soft-CappingAI Engineering & LLMs · #transformers #stability #sampling
- +25 XPmediumServe Many LoRA Adapters in One BatchAI Engineering & LLMs · #inference #lora #batching
- +10 XPeasyTemperature Sampling for Data MixturesAI Engineering & LLMs · #training-data #multilingual #sampling
- +10 XPeasyNeedle-in-a-Haystack EvaluationAI Engineering & LLMs · #long-context #evaluation #benchmarks
- +10 XPeasyStop Reasoning When the Answer StabilisesAI Engineering & LLMs · #reasoning #inference #cost
- +25 XPmediumAssemble Streamed Tool CallsAI Engineering & LLMs · #streaming #tool-use #apis
- +10 XPeasyDetect System Prompt LeakageAI Engineering & LLMs · #safety #prompt-injection #n-grams
- +10 XPeasyEvaluate Embeddings on Semantic Similarity (STS)AI Engineering & LLMs · #embeddings #evaluation #statistics
- +25 XPmediumCheap-to-Expensive Model CascadesAI Engineering & LLMs · #routing #cost #evaluation
- +10 XPeasySentence-Window RetrievalAI Engineering & LLMs · #rag #retrieval #chunking
- +10 XPeasyStreaming Latency Metrics: TTFT, TPOT and ITLAI Engineering & LLMs · #inference #monitoring #performance
- +25 XPmediumInference FLOPs with Long ContextsAI Engineering & LLMs · #inference #scaling #capacity-planning
- +25 XPmediumSparse Learned Retrieval (SPLADE-Style)AI Engineering & LLMs · #retrieval #sparse-vectors #inverted-index
- +50 XPhardModel Merging: Task Arithmetic and TIESAI Engineering & LLMs · #model-merging #fine-tuning #llms
- +50 XPhardSimulate FP8 (E4M3) QuantisationAI Engineering & LLMs · #quantization #number-formats #training
- +10 XPeasySpotlighting Untrusted Text with DatamarkingAI Engineering & LLMs · #prompt-injection #safety #prompting
- +25 XPmediumLength-Controlled Win RatesAI Engineering & LLMs · #evaluation #llm-as-judge #bias
- +10 XPeasyLay Out Prompts for Cache HitsAI Engineering & LLMs · #prompt-caching #cost #latency
- +10 XPeasyLinear Regression via Gradient DescentMachine Learning · #regression #optimisation #numpy
- +10 XPeasyPrecision, Recall & F1Machine Learning · #metrics #classification
- +25 XPmediumK-Means: Assign & UpdateMachine Learning · #clustering #unsupervised
- +25 XPmediumLogistic Regression from ScratchMachine Learning · #classification #optimisation
- +50 XPhardDecision Tree: Best Gini SplitMachine Learning · #trees #classification
- +10 XPeasyK-Fold Cross-Validation SplitsMachine Learning · #evaluation #numpy
- +10 XPeasyk-Nearest Neighbours ClassifierMachine Learning · #classification #numpy
- +25 XPmediumROC AUC from ScratchMachine Learning · #evaluation #classification #numpy
- +25 XPmediumPCA via SVDMachine Learning · #dimensionality-reduction #linear-algebra #numpy
- +10 XPeasyMulticlass Confusion Matrix & Macro-F1Machine Learning · #evaluation #classification #numpy
- +25 XPmediumNaive Bayes Text ClassifierMachine Learning · #classification #nlp #probability
- +25 XPmediumRidge Regression (Closed Form)Machine Learning · #regression #regularization #linear-algebra
- +10 XPeasyEarly Stopping TrackerMachine Learning · #training #overfitting
- +10 XPeasyOne-Hot Encoder with Unseen CategoriesMachine Learning · #preprocessing #categorical #numpy
- +25 XPmediumPermutation Feature ImportanceMachine Learning · #interpretability #evaluation #numpy
- +50 XPhardGradient Boosting with Decision StumpsMachine Learning · #boosting #ensembles #regression
- +25 XPmediumk-means++ InitialisationMachine Learning · #clustering #sampling #numpy
- +25 XPmediumModel Calibration: Expected Calibration ErrorMachine Learning · #evaluation #calibration #probability
- +50 XPhardDBSCAN Density-Based ClusteringMachine Learning · #clustering #unsupervised #numpy
- +25 XPmediumSoftmax (Multinomial) RegressionMachine Learning · #classification #gradient-descent #numpy
- +25 XPmediumTF-IDF VectoriserMachine Learning · #nlp #features #search
- +25 XPmediumSmoothed Target EncodingMachine Learning · #features #categorical #leakage
- +10 XPeasyThe PerceptronMachine Learning · #classification #linear-models #history
- +10 XPeasyRBF Kernel Matrix (Vectorised)Machine Learning · #kernels #numpy #vectorization
- +25 XPmediumPrecision-Recall Curve & Average PrecisionMachine Learning · #evaluation #ranking #classification
- +50 XPhardLasso Regression by Coordinate DescentMachine Learning · #regression #regularization #sparsity
- +10 XPeasyPolynomial Features and OverfittingMachine Learning · #features #regression #overfitting
- +25 XPmediumSMOTE: Synthetic Minority OversamplingMachine Learning · #imbalanced-data #sampling #numpy
- +50 XPhardDecision Tree RegressorMachine Learning · #trees #regression #recursion
- +25 XPmediumLinear SVM with Hinge LossMachine Learning · #classification #svm #optimization
- +50 XPhardGaussian Mixture Model: One EM StepMachine Learning · #clustering #probability #em
- +10 XPeasyThe Hashing TrickMachine Learning · #features #nlp #hashing
- +25 XPmediumBagging: Bootstrap AggregationMachine Learning · #ensembles #bootstrap #variance
- +50 XPhardRecommendations with Alternating Least SquaresMachine Learning · #recommenders #matrix-factorization #linear-algebra
- +10 XPeasyMulti-Label Classification MetricsMachine Learning · #metrics #multi-label #classification
- +25 XPmediumGrid Search with Cross-ValidationMachine Learning · #model-selection #cross-validation #hyperparameters
- +50 XPhardAnomaly Scores with Isolation TreesMachine Learning · #anomaly-detection #trees #unsupervised
- +10 XPeasyDiagnose Bias vs Variance from Learning CurvesMachine Learning · #model-selection #diagnostics #bias-variance
- +10 XPeasySilhouette Score for ClusteringMachine Learning · #clustering #metrics #unsupervised
- +25 XPmediumHierarchical Agglomerative ClusteringMachine Learning · #clustering #unsupervised #linkage
- +50 XPhardAdaBoost with Decision StumpsMachine Learning · #ensembles #boosting #classification
- +25 XPmediumQuantile Regression with Pinball LossMachine Learning · #regression #uncertainty #loss-functions
- +25 XPmediumFisher's Linear DiscriminantMachine Learning · #classification #dimensionality-reduction #linear-algebra
- +10 XPeasyFeature Selection with Mutual InformationMachine Learning · #feature-selection #information-theory
- +25 XPmediumGaussian Naive BayesMachine Learning · #classification #probabilistic-models #bayes
- +25 XPmediumKernel Ridge Regression and Fast Leave-One-OutMachine Learning · #kernels #regression #cross-validation
- +50 XPhardt-SNE: Affinities, KL and GradientMachine Learning · #dimensionality-reduction #visualization #optimization
- +25 XPmediumSemi-Supervised Label PropagationMachine Learning · #semi-supervised #graphs #classification
- +10 XPeasyChoose a Threshold by Business CostMachine Learning · #classification #decision-theory #metrics
- +10 XPeasyTime-Series Cross-Validation SplitsMachine Learning · #cross-validation #time-series #leakage
- +25 XPmediumSplit Conformal PredictionMachine Learning · #uncertainty #conformal #calibration
- +10 XPeasyPlatt Scaling for Classifier ScoresMachine Learning · #calibration #classification #logistic-regression
- +25 XPmediumk-Medoids ClusteringMachine Learning · #clustering #unsupervised #distances
- +10 XPeasyPartial Dependence and ICE CurvesMachine Learning · #interpretability #model-agnostic #explainability
- +50 XPhardExact Shapley Values for a PredictionMachine Learning · #interpretability #game-theory #explainability
- +50 XPhardSpectral ClusteringMachine Learning · #clustering #graphs #linear-algebra
- +25 XPmediumRobust Regression with Huber Loss (IRLS)Machine Learning · #regression #robust-statistics #outliers
- +25 XPmediumRecursive Feature EliminationMachine Learning · #feature-selection #regularization #linear-models
- +25 XPmediumStacking with Out-of-Fold PredictionsMachine Learning · #ensembles #cross-validation #leakage
- +10 XPeasyKernel Density Estimation and Bandwidth SelectionMachine Learning · #density-estimation #nonparametric #statistics
- +25 XPmediumItem-Item Collaborative FilteringMachine Learning · #recommenders #similarity #collaborative-filtering
- +10 XPeasyGroup Fairness MetricsMachine Learning · #fairness #evaluation #responsible-ai
- +25 XPmediumSparse Logistic Regression with Proximal GradientMachine Learning · #regularization #sparsity #optimization
- +25 XPmediumMean-Shift ClusteringMachine Learning · #clustering #density #unsupervised
- +50 XPhardGaussian Process RegressionMachine Learning · #bayesian #kernels #uncertainty
- +25 XPmediumHidden Markov Models: Forward and ViterbiMachine Learning · #sequence-models #dynamic-programming #probabilistic-models
- +10 XPeasyHard, Soft and Weighted VotingMachine Learning · #ensembles #classification
- +25 XPmediumBias–Variance Decomposition by SimulationMachine Learning · #model-selection #bias-variance #simulation
- +10 XPeasyMin-Max ScalerMachine Learning · #preprocessing #scaling
- +10 XPeasyRegression Metrics: MAE, RMSE and R²Machine Learning · #metrics #regression
- +10 XPeasyBinary Log LossMachine Learning · #metrics #classification #probability
- +25 XPmediumStratified Train/Test SplitMachine Learning · #data-splitting #validation #imbalance
- +10 XPeasyEntropy and Information GainMachine Learning · #decision-trees #information-theory
- +10 XPeasyLinear Regression by the Normal EquationMachine Learning · #regression #linear-algebra
- +10 XPeasyWeighted Least SquaresMachine Learning · #regression #linear-algebra
- +10 XPeasyChoose PCA Components by Explained VarianceMachine Learning · #dimensionality-reduction #pca
- +10 XPeasyK-Means Inertia and the ElbowMachine Learning · #clustering #k-means #model-selection
- +10 XPeasyOutlier Flags: IQR and Z-ScoreMachine Learning · #outliers #statistics #data-quality
- +10 XPeasyMatthews Correlation CoefficientMachine Learning · #metrics #classification #imbalance
- +10 XPeasyCohen's KappaMachine Learning · #metrics #agreement
- +25 XPmediumBrier Score and ReliabilityMachine Learning · #metrics #calibration #probability
- +25 XPmediumCumulative Gains and LiftMachine Learning · #metrics #marketing #ranking
- +25 XPmediumPick the Threshold for a Target PrecisionMachine Learning · #metrics #thresholds #classification
- +10 XPeasyBalanced Class WeightsMachine Learning · #imbalance #preprocessing
- +10 XPeasyOrdinal Encoder with Unknown CategoriesMachine Learning · #preprocessing #categorical
- +10 XPeasyQuantile BinningMachine Learning · #preprocessing #discretization
- +25 XPmediumDistance-Weighted k-NN RegressionMachine Learning · #knn #regression
- +25 XPmediumBernoulli Naive BayesMachine Learning · #naive-bayes #classification #text
- +25 XPmediumOne-vs-Rest Multiclass WrapperMachine Learning · #classification #multiclass #logistic-regression
- +25 XPmediumMini-Batch SGD with a Decaying Learning RateMachine Learning · #optimization #logistic-regression #sgd
- +50 XPhardElastic Net by Coordinate DescentMachine Learning · #regression #regularization #optimization
- +50 XPhardRandom Forest of StumpsMachine Learning · #ensembles #bagging #decision-trees
- +50 XPhardQuadratic Discriminant AnalysisMachine Learning · #classification #generative-models #gaussian
- +25 XPmediumPCA and ZCA WhiteningMachine Learning · #preprocessing #pca #linear-algebra
- +50 XPhardNon-Negative Matrix FactorisationMachine Learning · #matrix-factorization #unsupervised #topic-modeling
- +25 XPmediumMini-Batch K-MeansMachine Learning · #clustering #k-means #scalability
- +25 XPmediumDavies-Bouldin IndexMachine Learning · #clustering #metrics
- +50 XPhardAdjusted Rand IndexMachine Learning · #clustering #metrics #combinatorics
- +25 XPmediumNormalised Mutual InformationMachine Learning · #clustering #metrics #information-theory
- +25 XPmediumk-NN ImputationMachine Learning · #preprocessing #missing-data #knn
- +25 XPmediumChoose a Polynomial Degree by ValidationMachine Learning · #model-selection #overfitting #regression
- +50 XPhardLOWESS Local RegressionMachine Learning · #regression #smoothing #nonparametric
- +50 XPhardIsotonic Regression (PAVA)Machine Learning · #regression #calibration #algorithms
- +25 XPmediumRanking Metrics: MAP@k and NDCG@kMachine Learning · #metrics #ranking #recommenders
- +25 XPmediumWeight of Evidence and Information ValueMachine Learning · #feature-engineering #credit-risk #categorical
- +25 XPmediumPassive-Aggressive Online ClassifierMachine Learning · #online-learning #classification #linear-models
- +50 XPhardBayesian Linear RegressionMachine Learning · #bayesian #regression #uncertainty
- +25 XPmediumRANSAC Line FittingMachine Learning · #robust-statistics #outliers #regression
- +25 XPmediumUser-Based Collaborative FilteringMachine Learning · #recommenders #similarity #collaborative-filtering
- +50 XPhardFrequent Itemsets with AprioriMachine Learning · #association-rules #market-basket #algorithms
- +25 XPmediumMarkov Chain Stationary DistributionMachine Learning · #probability #markov-chains #linear-algebra
- +25 XPmediumHMM Forward AlgorithmMachine Learning · #hidden-markov-models #dynamic-programming #probability
- +50 XPhardEM for a Mixture of BernoullisMachine Learning · #expectation-maximization #clustering #mixture-models
- +10 XPeasyPredict with a Serialised Decision TreeMachine Learning · #decision-trees #inference
- +50 XPhardGradient Boosting for ClassificationMachine Learning · #boosting #ensembles #classification
- +25 XPmediumXGBoost Split GainMachine Learning · #boosting #decision-trees #optimization
- +25 XPmediumMahalanobis Distance OutliersMachine Learning · #outliers #statistics #multivariate
- +25 XPmediumLeakage-Free Cross-ValidationMachine Learning · #validation #data-leakage #pipelines
- +25 XPmediumDense Layer Forward & BackwardDeep Learning · #backprop #neural-networks
- +25 XPmediumSoftmax Cross-Entropy & Its GradientDeep Learning · #loss #classification #backprop
- +25 XPmediumAdam Optimiser StepDeep Learning · #optimisation #training
- +10 XPeasyLayer NormalisationDeep Learning · #normalisation #transformers
- +10 XPeasyReLU & GELU ActivationsDeep Learning · #activations #numpy
- +25 XPmediumInverted DropoutDeep Learning · #regularization #training #numpy
- +25 XPmedium1-D Convolution Forward PassDeep Learning · #cnn #numpy
- +10 XPeasySinusoidal Positional EncodingDeep Learning · #transformers #embeddings #numpy
- +25 XPmediumBatch Normalisation: Train vs InferenceDeep Learning · #normalisation #training #numpy
- +10 XPeasyLearning Rate: Warmup + Cosine DecayDeep Learning · #training #optimization #llm
- +10 XPeasyGradient Clipping by Global NormDeep Learning · #training #optimization #numpy
- +25 XPmedium2-D Max PoolingDeep Learning · #cnn #numpy
- +50 XPhardLSTM Cell Forward PassDeep Learning · #rnn #sequence-models #numpy
- +25 XPmediumSoftmax Cross-Entropy GradientDeep Learning · #backprop #gradients #numpy
- +10 XPeasyXavier and He Weight InitialisationDeep Learning · #initialization #training #numpy
- +50 XPhardBuild a Tiny Autograd EngineDeep Learning · #autograd #backprop #classes
- +50 XPhardTrain an MLP on XOR with Manual BackpropDeep Learning · #backprop #training #numpy
- +50 XPhardLayerNorm Backward PassDeep Learning · #backprop #normalization #gradients
- +25 XPmediumWord2Vec Skip-Gram with Negative SamplingDeep Learning · #embeddings #nlp #gradients
- +10 XPeasyCross-Entropy with Label SmoothingDeep Learning · #loss-functions #regularization #training
- +10 XPeasySGD with Momentum and NesterovDeep Learning · #optimization #training
- +10 XPeasyRMSNorm and SwiGLU (Llama's MLP Block)Deep Learning · #transformers #normalization #activations
- +25 XPmedium2-D Convolution Forward PassDeep Learning · #cnn #numpy #vision
- +25 XPmediumGRU Cell Forward PassDeep Learning · #rnn #sequence-models #numpy
- +25 XPmediumFocal Loss for Imbalanced DataDeep Learning · #loss-functions #imbalanced-data #detection
- +10 XPeasyRMSprop OptimiserDeep Learning · #optimization #training
- +10 XPeasyGlobal Average Pooling Classification HeadDeep Learning · #cnn #vision #numpy
- +25 XPmediumUpsampling: Nearest and BilinearDeep Learning · #vision #interpolation #numpy
- +25 XPmediumEmbedding Layer Backward (Scatter-Add)Deep Learning · #embeddings #backprop #numpy
- +25 XPmediumGradient AccumulationDeep Learning · #training #memory #optimization
- +50 XPhardBatchNorm Backward PassDeep Learning · #backprop #normalization #gradients
- +25 XPmediumResidual Block Forward and BackwardDeep Learning · #resnets #backprop #architectures
- +10 XPeasyStep, Exponential and One-Cycle LR SchedulesDeep Learning · #optimization #learning-rate #training
- +25 XPmediumDynamic Loss Scaling for Mixed PrecisionDeep Learning · #mixed-precision #fp16 #training
- +50 XPhardBackpropagate Through AttentionDeep Learning · #attention #backprop #transformers
- +50 XPhard1-D Convolution Forward and BackwardDeep Learning · #cnns #backprop #sequences
- +10 XPeasyConvolution Shape and Parameter CalculatorDeep Learning · #cnns #architectures #shapes
- +10 XPeasyExponential Moving Average of WeightsDeep Learning · #training #model-averaging #optimization
- +25 XPmediumTriplet Loss with Batch-Hard MiningDeep Learning · #metric-learning #embeddings #loss-functions
- +25 XPmediumALiBi: Attention with Linear BiasesDeep Learning · #attention #positional-encoding #transformers
- +25 XPmediumVAE: Reparameterisation and the ELBODeep Learning · #generative-models #vae #probability
- +50 XPhardBackpropagation Through TimeDeep Learning · #rnns #backprop #sequences
- +25 XPmediumAdamW: Decoupled Weight DecayDeep Learning · #optimization #regularization #training
- +10 XPeasyCount a Transformer's ParametersDeep Learning · #transformers #architectures #capacity-planning
- +25 XPmediumGroup NormalisationDeep Learning · #normalization #cnns #architectures
- +10 XPeasyMixup and CutMix AugmentationDeep Learning · #augmentation #regularization #vision
- +25 XPmediumNext-Token Loss with Padding and Prompt MasksDeep Learning · #language-models #loss-functions #fine-tuning
- +25 XPmediumDiffusion Noise Schedules and the DDPM PosteriorDeep Learning · #diffusion #generative-models #probability
- +10 XPeasyLearning-Rate Range TestDeep Learning · #optimization #learning-rate #training
- +25 XPmediumFast Convolution with im2colDeep Learning · #cnns #performance #linear-algebra
- +25 XPmediumMax-Pooling Backward PassDeep Learning · #cnns #backprop #pooling
- +25 XPmediumForward and Backward Through a LoRA LayerDeep Learning · #fine-tuning #lora #backprop
- +10 XPeasySplit Images into ViT PatchesDeep Learning · #vision-transformers #tensors #reshaping
- +25 XPmediumPlan Activation CheckpointingDeep Learning · #memory #training #systems
- +10 XPeasyGradient CheckingDeep Learning · #backprop #debugging #testing
- +25 XPmediumAssemble a Pre-Norm Transformer BlockDeep Learning · #transformers #attention #architectures
- +25 XPmediumSpectral Normalisation by Power IterationDeep Learning · #regularization #gans #linear-algebra
- +10 XPeasyDiagnose Dead ReLUs and SaturationDeep Learning · #debugging #activations #training
- +10 XPeasyPad and Collate Variable-Length BatchesDeep Learning · #data-loading #nlp #batching
- +50 XPhardCTC Loss: The Forward AlgorithmDeep Learning · #speech #sequences #dynamic-programming
- +10 XPeasyThe Lookahead Optimiser WrapperDeep Learning · #optimization #training
- +25 XPmediumDepthwise and Pointwise ConvolutionsDeep Learning · #cnns #efficiency #mobile
- +10 XPeasyOptimizer Parameter Groups: What Not to DecayDeep Learning · #optimization #regularization #training
- +50 XPhardSimulate Ring All-ReduceDeep Learning · #distributed-training #systems #communication
- +25 XPmediumGradient Noise Scale and the Critical Batch SizeDeep Learning · #scaling #batch-size #training
- +10 XPeasyBERT-Style Masking for Masked Language ModellingDeep Learning · #nlp #pretraining #data-loading
- +10 XPeasySigmoid and Tanh with Their DerivativesDeep Learning · #activations #backprop
- +10 XPeasyMSE Loss Forward and BackwardDeep Learning · #losses #backprop
- +10 XPeasyLeaky ReLU, ELU and SELUDeep Learning · #activations
- +10 XPeasyNumerically Stable SoftmaxDeep Learning · #activations #numerics
- +10 XPeasyLog-Softmax and Negative Log-LikelihoodDeep Learning · #losses #numerics
- +10 XPeasySwish (SiLU) and MishDeep Learning · #activations
- +10 XPeasyBatched Linear LayerDeep Learning · #layers #linear-algebra
- +25 XPmediumBinary Cross-Entropy with LogitsDeep Learning · #losses #numerics
- +25 XPmediumMulticlass Hinge Loss and GradientDeep Learning · #losses #svm #backprop
- +25 XPmediumCosine Annealing with Warm RestartsDeep Learning · #learning-rate #schedules
- +25 XPmediumOne-Cycle Learning Rate PolicyDeep Learning · #learning-rate #schedules
- +10 XPeasyAdagradDeep Learning · #optimizers
- +25 XPmediumAdadeltaDeep Learning · #optimizers
- +50 XPhardLAMB: Layer-wise Adaptive Large-Batch OptimisationDeep Learning · #optimizers #large-batch
- +25 XPmediumNadam: Adam with Nesterov MomentumDeep Learning · #optimizers
- +10 XPeasyCounting MLP Parameters and MemoryDeep Learning · #architecture #memory
- +25 XPmediumReceptive Field of a CNNDeep Learning · #cnn #architecture
- +10 XPeasyAverage Pooling 2DDeep Learning · #cnn #pooling
- +25 XPmediumTransposed Convolution 1DDeep Learning · #cnn #upsampling
- +25 XPmediumDilated Causal ConvolutionDeep Learning · #cnn #sequence-models
- +10 XPeasyInstance NormalisationDeep Learning · #normalization #style-transfer
- +25 XPmediumWeight NormalisationDeep Learning · #normalization #reparameterization #backprop
- +25 XPmediumMonte Carlo Dropout UncertaintyDeep Learning · #uncertainty #dropout #bayesian
- +25 XPmediumBidirectional RNN Forward PassDeep Learning · #rnn #sequence-models
- +25 XPmediumBahdanau (Additive) AttentionDeep Learning · #attention #seq2seq
- +50 XPhardMulti-Head Self-Attention Forward PassDeep Learning · #attention #transformers
- +10 XPeasyBuilding Attention MasksDeep Learning · #attention #transformers #batching
- +25 XPmediumContrastive Loss for Siamese NetworksDeep Learning · #metric-learning #losses #embeddings
- +25 XPmediumSoft Dice Loss for SegmentationDeep Learning · #segmentation #losses #imbalance
- +25 XPmediumIoU and Generalised IoU for BoxesDeep Learning · #object-detection #geometry
- +25 XPmediumNon-Maximum SuppressionDeep Learning · #object-detection #algorithms
- +25 XPmediumGenerating Anchor BoxesDeep Learning · #object-detection #geometry
- +25 XPmediumFolding Batch Norm into a Linear LayerDeep Learning · #inference #normalization #optimization
- +25 XPmediumGAN Losses: Minimax and Non-SaturatingDeep Learning · #gans #losses #generative-models
- +10 XPeasyThe Reparameterisation TrickDeep Learning · #vae #generative-models #sampling
- +50 XPhardA Linear Autoencoder Learns PCADeep Learning · #autoencoders #pca #backprop
- +50 XPhardDDPM Reverse (Denoising) StepDeep Learning · #diffusion #generative-models #sampling
- +25 XPmediumDiagnosing Vanishing GradientsDeep Learning · #training-dynamics #activations #backprop
- +25 XPmediumXavier vs He InitialisationDeep Learning · #initialization #training-dynamics
- +10 XPeasyEmbeddingBag: Pooled LookupsDeep Learning · #embeddings #recommenders
- +25 XPmediumL2 Normalisation Layer and Its GradientDeep Learning · #embeddings #backprop #normalization
- +25 XPmediumHalf-Precision Range and Loss ScalingDeep Learning · #mixed-precision #numerics
- +25 XPmediumCross-Entropy with an Ignore IndexDeep Learning · #losses #sequence-models #batching
- +10 XPeasyTop-k AccuracyDeep Learning · #metrics #classification
- +25 XPmediumCalibrating a Network with Temperature ScalingDeep Learning · #calibration #uncertainty
- +25 XPmediumClass-Weighted Cross-EntropyDeep Learning · #losses #imbalance
- +50 XPhardSharpness-Aware Minimisation (SAM)Deep Learning · #optimizers #generalization
- +10 XPeasyPolynomial Decay with Linear Warm-upDeep Learning · #learning-rate #schedules
- +25 XPmediumPixel Shuffle (Sub-Pixel Convolution)Deep Learning · #upsampling #super-resolution #tensors
- +25 XPmediumSqueeze-and-Excitation BlockDeep Learning · #cnn #attention #architecture
- +10 XPeasyFlag Outliers with Z-ScoresData Science & Statistics · #statistics #cleaning
- +25 XPmediumpandas: Monthly Revenue by CohortData Science & Statistics · #pandas #groupby #cohorts
- +25 XPmediumA/B Test: Two-Proportion Z-TestData Science & Statistics · #experimentation #hypothesis-testing
- +25 XPmediumBootstrap Confidence IntervalData Science & Statistics · #statistics #resampling
- +10 XPeasyPearson Correlation from ScratchData Science & Statistics · #statistics #numpy
- +25 XPmediumExponentially Weighted Moving AverageData Science & Statistics · #time-series #numpy
- +10 XPeasyStandard Scaler Without Data LeakageData Science & Statistics · #preprocessing #leakage #numpy
- +10 XPeasyOutlier Detection with the IQR RuleData Science & Statistics · #statistics #outliers #numpy
- +25 XPmediumChi-Square Test of IndependenceData Science & Statistics · #statistics #hypothesis-testing #numpy
- +25 XPmediumpandas: Top Products per RegionData Science & Statistics · #pandas #groupby #ranking
- +10 XPeasyRegression Metrics: MAE, RMSE, R²Data Science & Statistics · #evaluation #regression #numpy
- +25 XPmediumStratified Train/Test SplitData Science & Statistics · #sampling #evaluation #numpy
- +25 XPmediumA/B Test Sample SizeData Science & Statistics · #experimentation #statistics
- +25 XPmediumpandas: Lag and Rolling FeaturesData Science & Statistics · #pandas #time-series #feature-engineering
- +50 XPhardKaplan–Meier Survival CurveData Science & Statistics · #survival-analysis #churn #statistics
- +50 XPhardMulti-Armed Bandit: UCB1Data Science & Statistics · #experimentation #reinforcement-learning #optimization
- +25 XPmediumSpot Simpson's ParadoxData Science & Statistics · #statistics #experimentation #pitfalls
- +25 XPmediumForecasting with Holt's Linear TrendData Science & Statistics · #time-series #forecasting
- +25 XPmediumWelch's t-Test for Two MeansData Science & Statistics · #statistics #hypothesis-testing #experimentation
- +25 XPmediumConfidence Interval for a Conversion Rate (Wilson)Data Science & Statistics · #statistics #confidence-intervals #experimentation
- +25 XPmediumMultiple Testing: Bonferroni and Benjamini–HochbergData Science & Statistics · #statistics #experimentation #multiple-testing
- +25 XPmediumMann–Whitney U TestData Science & Statistics · #statistics #non-parametric #hypothesis-testing
- +10 XPeasySpearman Rank CorrelationData Science & Statistics · #statistics #correlation
- +10 XPeasyEffect Size: Cohen's dData Science & Statistics · #statistics #experimentation
- +10 XPeasyWeighted Mean, Variance and Survey WeightsData Science & Statistics · #statistics #surveys #numpy
- +25 XPmediumAutocorrelation and Seasonality DetectionData Science & Statistics · #time-series #statistics
- +10 XPeasyFunnel Conversion from Event LogsData Science & Statistics · #product-analytics #funnels
- +25 XPmediumN-Day Retention CurveData Science & Statistics · #retention #cohorts #product-analytics
- +25 XPmediumpandas: Anti-Joins and Mismatched KeysData Science & Statistics · #pandas #joins #data-quality
- +10 XPeasyPivot Tables in pandasData Science & Statistics · #pandas #pivot #reporting
- +25 XPmediumImpute Missing Values by GroupData Science & Statistics · #pandas #missing-data #cleaning
- +10 XPeasyHistogram Binning RulesData Science & Statistics · #statistics #visualization #numpy
- +50 XPhardCUPED: Faster A/B Tests with Pre-Experiment DataData Science & Statistics · #ab-testing #variance-reduction #statistics
- +10 XPeasyMin-Max vs Robust ScalingData Science & Statistics · #preprocessing #outliers #numpy
- +25 XPmediumRolling Means with Missing DataData Science & Statistics · #time-series #numpy #missing-data
- +25 XPmediumPoint-in-Time Joins with merge_asofData Science & Statistics · #pandas #time-series #joins
- +50 XPhardDifference-in-DifferencesData Science & Statistics · #causal-inference #regression #statistics
- +25 XPmediumFill Missing Days and Roll Up by WeekData Science & Statistics · #pandas #time-series #resampling
- +10 XPeasyReshape Wide Data to LongData Science & Statistics · #pandas #reshaping #tidy-data
- +10 XPeasyCount Tags in Multi-Valued ColumnsData Science & Statistics · #pandas #strings #cleaning
- +25 XPmediumSessionise a ClickstreamData Science & Statistics · #pandas #product-analytics #time-series
- +25 XPmediumBuild an OLS Regression TableData Science & Statistics · #regression #statistics #inference
- +25 XPmediumClassical Seasonal DecompositionData Science & Statistics · #time-series #forecasting #smoothing
- +25 XPmediumThe Peeking Problem in A/B TestsData Science & Statistics · #ab-testing #simulation #statistics
- +50 XPhardInverse Propensity Weighting for Causal EffectsData Science & Statistics · #causal-inference #observational-data #logistic-regression
- +25 XPmediumBayesian A/B Testing with Beta PosteriorsData Science & Statistics · #ab-testing #bayesian #simulation
- +10 XPeasyWinsorise OutliersData Science & Statistics · #outliers #cleaning #statistics
- +25 XPmediumValidate a DataFrame Against ExpectationsData Science & Statistics · #data-quality #pandas #testing
- +10 XPeasyInequality: Gini Coefficient and Lorenz CurveData Science & Statistics · #statistics #inequality #concentration
- +25 XPmediumPermutation TestsData Science & Statistics · #hypothesis-testing #resampling #statistics
- +25 XPmediumRFM Customer SegmentationData Science & Statistics · #pandas #segmentation #marketing-analytics
- +10 XPeasyBenford's Law CheckData Science & Statistics · #fraud-detection #statistics #distributions
- +25 XPmediumThompson Sampling for Bernoulli BanditsData Science & Statistics · #bandits #bayesian #experimentation
- +25 XPmediumCatch Join Explosions Before They HappenData Science & Statistics · #pandas #joins #data-quality
- +10 XPeasyEstimate Price ElasticityData Science & Statistics · #economics #regression #pricing
- +50 XPhardHolt–Winters Seasonal ForecastingData Science & Statistics · #time-series #forecasting #exponential-smoothing
- +25 XPmediumA/B Testing Ratio Metrics with the Delta MethodData Science & Statistics · #ab-testing #variance #statistics
- +25 XPmediumKolmogorov–Smirnov Two-Sample TestData Science & Statistics · #hypothesis-testing #drift-detection #distributions
- +10 XPeasyPopulation Stability IndexData Science & Statistics · #monitoring #drift-detection #credit-risk
- +50 XPhardUplift Modelling and the Qini CurveData Science & Statistics · #causal-inference #uplift #marketing-analytics
- +25 XPmediumDetect Shifts with CUSUMData Science & Statistics · #monitoring #changepoint-detection #quality-control
- +10 XPeasyCrosstabs, Support, Confidence and LiftData Science & Statistics · #pandas #association-rules #market-basket
- +10 XPeasyCramér's V for Categorical AssociationData Science & Statistics · #statistics #categorical-data #feature-selection
- +10 XPeasyDescriptive Statistics SummaryData Science & Statistics · #statistics #eda
- +10 XPeasyPercentiles by Linear InterpolationData Science & Statistics · #statistics #quantiles
- +10 XPeasyWeighted MedianData Science & Statistics · #statistics #robust-statistics
- +10 XPeasySimple and Weighted Moving AveragesData Science & Statistics · #time-series #smoothing
- +10 XPeasyShare of Group Total with transformData Science & Statistics · #pandas #groupby
- +25 XPmediumYear-over-Year Growth by MonthData Science & Statistics · #pandas #time-series
- +25 XPmediumLatest Record per Key in pandasData Science & Statistics · #pandas #deduplication
- +10 XPeasyBinning Ages with pd.cutData Science & Statistics · #pandas #binning
- +10 XPeasyConfidence Interval for a MeanData Science & Statistics · #statistics #inference
- +10 XPeasyOne-Sample z-TestData Science & Statistics · #hypothesis-testing #statistics
- +25 XPmediumStatistical Power of an A/B TestData Science & Statistics · #ab-testing #power-analysis
- +10 XPeasyPaired t-StatisticData Science & Statistics · #hypothesis-testing #statistics
- +25 XPmediumOne-Way ANOVA F-StatisticData Science & Statistics · #hypothesis-testing #anova
- +25 XPmediumChi-Square Goodness of FitData Science & Statistics · #hypothesis-testing #categorical
- +50 XPhardFisher's Exact TestData Science & Statistics · #hypothesis-testing #small-samples #combinatorics
- +25 XPmediumExact Sign TestData Science & Statistics · #hypothesis-testing #nonparametric
- +25 XPmediumKendall's Tau-bData Science & Statistics · #correlation #nonparametric #ranking
- +10 XPeasyLinear Trend ForecastData Science & Statistics · #forecasting #time-series #regression
- +25 XPmediumSimple Exponential Smoothing with a Tuned AlphaData Science & Statistics · #forecasting #time-series #smoothing
- +25 XPmediumFitting an AR(1) ModelData Science & Statistics · #time-series #forecasting #statistics
- +25 XPmediumForecast Errors: MAPE, sMAPE and MASEData Science & Statistics · #forecasting #metrics
- +25 XPmediumRolling z-Score Anomaly DetectionData Science & Statistics · #anomaly-detection #time-series
- +25 XPmediumLife Table Hazard RatesData Science & Statistics · #survival-analysis #churn
- +25 XPmediumCumulative Revenue per Customer by CohortData Science & Statistics · #cohort-analysis #ltv #pandas
- +25 XPmediumJackknife Standard ErrorData Science & Statistics · #resampling #statistics #uncertainty
- +50 XPhardSequential Probability Ratio TestData Science & Statistics · #ab-testing #sequential-testing #hypothesis-testing
- +25 XPmediumEpsilon-Greedy BanditData Science & Statistics · #bandits #experimentation #reinforcement-learning
- +10 XPeasySample Ratio Mismatch CheckData Science & Statistics · #ab-testing #data-quality #hypothesis-testing
- +25 XPmediumPost-Stratified EstimatesData Science & Statistics · #survey-statistics #ab-testing #variance-reduction
- +50 XPhardInstrumental Variables with 2SLSData Science & Statistics · #causal-inference #regression #econometrics
- +50 XPhardNearest-Neighbour Propensity Score MatchingData Science & Statistics · #causal-inference #matching #observational-studies
- +25 XPmediumInterrupted Time Series (Segmented Regression)Data Science & Statistics · #causal-inference #time-series #regression
- +25 XPmediumAssociation Rules: Support, Confidence and LiftData Science & Statistics · #market-basket #association-rules
- +25 XPmediumMonthly Churn Rate from SubscriptionsData Science & Statistics · #pandas #churn #subscriptions
- +10 XPeasyNet Promoter Score with a Margin of ErrorData Science & Statistics · #metrics #surveys
- +10 XPeasyCompound Annual Growth RateData Science & Statistics · #finance #growth
- +25 XPmediumRolling Median with Two HeapsData Science & Statistics · #algorithms #time-series #robust-statistics
- +10 XPeasyABC Inventory AnalysisData Science & Statistics · #operations #pareto
- +25 XPmediumSample Size for Comparing Two MeansData Science & Statistics · #ab-testing #power-analysis
- +10 XPeasyMost Correlated Feature PairsData Science & Statistics · #eda #correlation #feature-selection
- +25 XPmediumVariance Inflation FactorsData Science & Statistics · #regression #multicollinearity #feature-selection
- +25 XPmediumPartial CorrelationData Science & Statistics · #correlation #causal-inference #statistics
- +10 XPeasyShannon and Simpson DiversityData Science & Statistics · #statistics #information-theory
- +25 XPmediumWeighted Reservoir SamplingData Science & Statistics · #sampling #streaming #algorithms
- +25 XPmediumNeyman Allocation for Stratified SamplingData Science & Statistics · #sampling #survey-statistics #optimization
- +25 XPmediumWeighted Means and Kish's Effective Sample SizeData Science & Statistics · #survey-statistics #weighting
- +10 XPeasyProfiling a DataFrameData Science & Statistics · #pandas #data-quality #eda
- +10 XPeasyRobust z-Scores with the MADData Science & Statistics · #outliers #robust-statistics
- +25 XPmediumChoosing a Box-Cox TransformData Science & Statistics · #transformations #statistics #normality
- +25 XPmediumRolling 7-Day Active UsersData Science & Statistics · #pandas #engagement #time-series
- +10 XPeasyRevenue by CountrySQL & Analytics · #joins #group-by
- +10 XPeasyCustomers Who Never OrderedSQL & Analytics · #left-join #anti-join
- +25 XPmediumRunning Total per CustomerSQL & Analytics · #window-functions
- +50 XPhardTop Customer Each MonthSQL & Analytics · #window-functions #cte #ranking
- +10 XPeasyRepeat CustomersSQL & Analytics · #group-by #having #joins
- +25 XPmediumMonth-over-Month Revenue GrowthSQL & Analytics · #window-functions #lag #dates
- +25 XPmediumDays from Signup to First OrderSQL & Analytics · #dates #aggregation #activation
- +25 XPmediumRank Customers Within Each CountrySQL & Analytics · #window-functions #ranking #left-join
- +10 XPeasyAverage Order Value by CountrySQL & Analytics · #aggregation #joins
- +10 XPeasySecond-Highest Order TotalSQL & Analytics · #subqueries #interview
- +25 XPmediumRolling Average of the Last Two OrdersSQL & Analytics · #window-functions #frames
- +25 XPmediumEach Country's Share of RevenueSQL & Analytics · #window-functions #aggregation
- +10 XPeasyMonthly Active CustomersSQL & Analytics · #aggregation #dates #distinct
- +25 XPmediumDays Between a Customer's OrdersSQL & Analytics · #window-functions #lag #dates
- +50 XPhardCustomers Who Ordered Every MonthSQL & Analytics · #relational-division #having #subqueries
- +50 XPhardLongest Streak of Consecutive Ordering MonthsSQL & Analytics · #gaps-and-islands #window-functions #cte
- +50 XPhardCohort Retention TableSQL & Analytics · #cohorts #retention #dates
- +25 XPmediumPivot: Revenue by Country and MonthSQL & Analytics · #pivot #conditional-aggregation #case
- +25 XPmediumMedian Order Value (No MEDIAN Function)SQL & Analytics · #window-functions #statistics #interview
- +25 XPmediumCustomers Who Came Back Within 30 DaysSQL & Analytics · #window-functions #retention #self-join
- +10 XPeasySign-ups per MonthSQL & Analytics · #aggregation #dates
- +25 XPmediumOrders Above the Customer's Own AverageSQL & Analytics · #window-functions #comparison
- +10 XPeasyFirst and Last Order per CustomerSQL & Analytics · #aggregation #dates
- +10 XPeasyRevenue by Day of the WeekSQL & Analytics · #dates #aggregation
- +25 XPmediumCustomer Spend Quartiles with NTILESQL & Analytics · #window-functions #segmentation
- +25 XPmediumReport with a Grand Total RowSQL & Analytics · #union #reporting
- +10 XPeasyRepeat Purchase RateSQL & Analytics · #aggregation #subqueries #retention
- +25 XPmediumTop Two Orders in Each CountrySQL & Analytics · #window-functions #top-n
- +50 XPhardCumulative Customer Count by MonthSQL & Analytics · #window-functions #growth #cte
- +25 XPmediumChange from the Previous OrderSQL & Analytics · #window-functions #lag
- +25 XPmediumAverage Days Between OrdersSQL & Analytics · #window-functions #dates #aggregation
- +10 XPeasyPairs of Customers in the Same Country (Self-Join)SQL & Analytics · #self-join #joins
- +10 XPeasyEach Customer's Latest OrderSQL & Analytics · #subqueries #correlated-subqueries
- +25 XPmediumFind Duplicate OrdersSQL & Analytics · #group-by #having #data-quality
- +10 XPeasyShare of Customers by CountrySQL & Analytics · #aggregation #window-functions #percentages
- +10 XPeasyCustomer Spend Including Non-BuyersSQL & Analytics · #left-join #coalesce #nulls
- +50 XPhardPareto: Cumulative Revenue ShareSQL & Analytics · #window-functions #cte #pareto
- +10 XPeasyBucket Orders by SizeSQL & Analytics · #case #aggregation
- +25 XPmediumFirst-Order vs Repeat RevenueSQL & Analytics · #window-functions #retention #aggregation
- +25 XPmediumFind Lapsed CustomersSQL & Analytics · #dates #having #churn
- +25 XPmediumFind Gaps in a Sequence of IDsSQL & Analytics · #recursive-cte #data-quality
- +25 XPmediumOrders per Customer by Signup CohortSQL & Analytics · #cohorts #left-join #aggregation
- +50 XPhardMonthly Revenue with a Date SpineSQL & Analytics · #recursive-cte #dates #time-series
- +10 XPeasyCustomers Active in Two Months (INTERSECT)SQL & Analytics · #set-operations #subqueries
- +25 XPmediumWhere Does Each Order Rank? (PERCENT_RANK, CUME_DIST)SQL & Analytics · #window-functions #percentiles
- +10 XPeasyBuild Tags with String FunctionsSQL & Analytics · #strings #functions
- +25 XPmediumTime to Second PurchaseSQL & Analytics · #window-functions #left-join #nulls
- +10 XPeasyWeekly Revenue with strftimeSQL & Analytics · #dates #aggregation
- +50 XPhardRolling 30-Day Revenue (RANGE Frames)SQL & Analytics · #window-functions #window-frames #time-series
- +10 XPeasyWho Stopped Ordering? (EXCEPT)SQL & Analytics · #set-operations #churn
- +10 XPeasyCustomers with a Big Order (EXISTS)SQL & Analytics · #subqueries #exists
- +10 XPeasyGroup Messy Missing ValuesSQL & Analytics · #nulls #cleaning #coalesce
- +25 XPmediumCompare Each Order to the First (FIRST_VALUE)SQL & Analytics · #window-functions #first-value
- +25 XPmediumA Complete Customer × Month Grid (CROSS JOIN)SQL & Analytics · #cross-join #left-join #reporting
- +50 XPhardGaps and Islands: Consecutive Order DaysSQL & Analytics · #window-functions #gaps-and-islands #dates
- +10 XPeasyOrder Value HistogramSQL & Analytics · #aggregation #bucketing
- +10 XPeasyCountries Where Nobody Has OrderedSQL & Analytics · #not-exists #subqueries
- +25 XPmediumRecord-Breaking Orders (Running MAX)SQL & Analytics · #window-functions #window-frames
- +25 XPmediumCustomers Whose Orders Keep GrowingSQL & Analytics · #window-functions #lag #having
- +25 XPmediumTrimmed Mean per CountrySQL & Analytics · #window-functions #robust-statistics
- +50 XPhard30-Day Conversion by Signup CohortSQL & Analytics · #cohorts #dates #conversion
- +10 XPeasyEach Country Against the AverageSQL & Analytics · #window-functions #aggregation
- +25 XPmediumDeduplicate Records, Keeping the LatestSQL & Analytics · #window-functions #deduplication #data-quality
- +50 XPhardForward-Fill Missing ValuesSQL & Analytics · #window-functions #nulls #time-series
- +25 XPmediumTop Spender per Country, Keeping TiesSQL & Analytics · #window-functions #rank #top-n
- +25 XPmediumMedian Order Value per CountrySQL & Analytics · #window-functions #median #statistics
- +25 XPmediumMonth-over-Month Change by CountrySQL & Analytics · #window-functions #lag #growth
- +10 XPeasyOrders in a Date RangeSQL & Analytics · #filtering #dates
- +10 XPeasyCustomers Whose Names Contain a LetterSQL & Analytics · #filtering #strings
- +10 XPeasyRevenue by QuarterSQL & Analytics · #aggregation #dates
- +25 XPmediumLargest Order in Each CountrySQL & Analytics · #window-functions #joins
- +25 XPmediumCustomers Who Ordered in Their Signup MonthSQL & Analytics · #joins #dates #exists
- +10 XPeasyAverage Orders per CustomerSQL & Analytics · #aggregation #subqueries
- +25 XPmediumOrders in the Top QuartileSQL & Analytics · #window-functions #ntile
- +25 XPmediumPercent Rank of Each OrderSQL & Analytics · #window-functions #ranking
- +25 XPmediumCumulative Distribution of Customer SpendSQL & Analytics · #window-functions #distributions
- +25 XPmediumList Each Customer's Orders in One RowSQL & Analytics · #aggregation #strings
- +10 XPeasyCountries with More Than One CustomerSQL & Analytics · #aggregation #having
- +25 XPmediumCustomers Whose Every Order Exceeds 75SQL & Analytics · #aggregation #having #not-exists
- +50 XPhardLongest Gap Between a Customer's OrdersSQL & Analytics · #window-functions #dates
- +10 XPeasyWeekend OrdersSQL & Analytics · #dates #filtering
- +25 XPmediumOrders from New vs Returning CustomersSQL & Analytics · #window-functions #cohorts
- +10 XPeasyDense Rank of Order TotalsSQL & Analytics · #window-functions #ranking
- +10 XPeasyPaginating ResultsSQL & Analytics · #pagination #limit-offset
- +25 XPmediumDays in March Without Any OrdersSQL & Analytics · #recursive-cte #dates #anti-join
- +10 XPeasyEach Order's Share of the Customer's SpendSQL & Analytics · #window-functions #aggregation
- +25 XPmediumMonthly Revenue with a Column per MarketSQL & Analytics · #pivot #conditional-aggregation
- +25 XPmediumA Combined Activity TimelineSQL & Analytics · #union #events
- +10 XPeasyCustomer Initials and Name LengthsSQL & Analytics · #strings
- +25 XPmediumRevenue in a Customer's First 30 DaysSQL & Analytics · #dates #joins #aggregation
- +25 XPmediumHow Dependent Is Each Country on Its Top Customer?SQL & Analytics · #window-functions #concentration
- +10 XPeasyAverage Order vs Average of Customer AveragesSQL & Analytics · #aggregation #subqueries
- +25 XPmediumCustomers Spending Above Their Country's AverageSQL & Analytics · #window-functions #comparison
- +10 XPeasyThe Busiest MonthSQL & Analytics · #aggregation #limit
- +25 XPmediumSubtotals and a Grand TotalSQL & Analytics · #union #rollup #reporting
- +10 XPeasyNumbering Each Customer's OrdersSQL & Analytics · #window-functions #row-number
- +25 XPmediumRevenue After a Customer's First MonthSQL & Analytics · #cohorts #joins #dates
- +25 XPmediumBig Spenders per Country, Including ZerosSQL & Analytics · #joins #aggregation #left-join
- +10 XPeasyShare of Customers Who Have OrderedSQL & Analytics · #aggregation #conversion
- +10 XPeasyRanking Months by RevenueSQL & Analytics · #window-functions #aggregation
- +25 XPmediumOrders Placed on the Same DaySQL & Analytics · #self-join #dates
- +10 XPeasyDays Since the Previous Order (Store-Wide)SQL & Analytics · #window-functions #dates
- +25 XPmediumMonthly Revenue Indexed to the First MonthSQL & Analytics · #window-functions #indexing
- +25 XPmediumRanking Countries Two WaysSQL & Analytics · #window-functions #aggregation
- +25 XPmediumCountries with Exactly One Buying CustomerSQL & Analytics · #aggregation #having #joins
- +10 XPeasySmall and Large Orders per CustomerSQL & Analytics · #conditional-aggregation
- +25 XPmediumEach Customer's Second-Largest OrderSQL & Analytics · #window-functions #ranking
- +10 XPeasyCustomers Who Never Ordered, by CountrySQL & Analytics · #anti-join #aggregation
- +10 XPeasyLargest Order So FarSQL & Analytics · #window-functions #running-aggregates
- +25 XPmediumCustomer Spend Change Month over MonthSQL & Analytics · #window-functions #aggregation
- +25 XPmediumEach Order Compared with the Customer's AverageSQL & Analytics · #window-functions #comparison
- +25 XPmediumDaily Revenue with Zero DaysSQL & Analytics · #recursive-cte #left-join #dates
- +10 XPeasyTop Revenue Days with TiesSQL & Analytics · #window-functions #ranking
- +10 XPeasySignups by Day of the WeekSQL & Analytics · #dates #aggregation
- +25 XPmediumBest Day in Each MonthSQL & Analytics · #window-functions #aggregation
- +25 XPmediumSpend Rank and Gap to the Next CustomerSQL & Analytics · #window-functions #ranking
- +10 XPeasyEach Order's Share of Its MonthSQL & Analytics · #window-functions #aggregation
- +25 XPmediumCustomers Active in Both Halves of the PeriodSQL & Analytics · #set-operations #dates
- +25 XPmediumFirst Order Size vs Later SpendSQL & Analytics · #cohorts #window-functions #case
- +25 XPmediumTime from Signup to First Order, BucketedSQL & Analytics · #dates #case #aggregation
- +25 XPmediumCumulative Revenue within Each CountrySQL & Analytics · #window-functions #running-aggregates
- +25 XPmediumCustomers Quiet for 30+ DaysSQL & Analytics · #dates #aggregation #churn
- +10 XPeasyTop Words by FrequencyPython Foundations · #strings #collections
- +10 XPeasyFlatten Arbitrarily Nested ListsPython Foundations · #recursion #generators
- +25 XPmediumBuild an LRU CachePython Foundations · #design #data-structures
- +10 XPeasyGroup AnagramsPython Foundations · #dicts #strings
- +25 XPmediumToken Bucket Rate LimiterPython Foundations · #classes #systems #apis
- +25 XPmediumRetry Decorator with Exponential BackoffPython Foundations · #decorators #apis #reliability
- +10 XPeasyParse and Summarise Log FilesPython Foundations · #regex #strings #collections
- +10 XPeasyLazy Batching GeneratorPython Foundations · #generators #iterators
- +10 XPeasyTiming Context ManagerPython Foundations · #context-managers #classes
- +25 XPmediumMemoize with a Time-to-LivePython Foundations · #decorators #caching #closures
- +10 XPeasyValidated DataclassesPython Foundations · #dataclasses #validation #classes
- +10 XPeasyCSV Sales ReportPython Foundations · #csv #parsing #collections
- +10 XPeasyDeep-Merge Configuration DictsPython Foundations · #dicts #recursion #config
- +50 XPhardArithmetic Expression EvaluatorPython Foundations · #parsing #recursion #strings
- +50 XPhardMini JSON Schema ValidatorPython Foundations · #validation #recursion #structured-output
- +10 XPeasyEvent Emitter (Pub/Sub)Python Foundations · #design #callbacks #classes
- +10 XPeasyHuman-Readable Sizes and DurationsPython Foundations · #strings #formatting
- +25 XPmediumBuild a Mini Command-Line ParserPython Foundations · #parsing #cli #design
- +25 XPmediumNormalise a File PathPython Foundations · #strings #stacks #security
- +10 XPeasyRun-Length EncodingPython Foundations · #strings #compression
- +10 XPeasyRoman NumeralsPython Foundations · #strings #parsing
- +10 XPeasyDeduplicate Sign-ups by Normalised EmailPython Foundations · #strings #dedup #data-cleaning
- +25 XPmediumSemantic Version SortingPython Foundations · #parsing #sorting #devtools
- +25 XPmediumCircuit BreakerPython Foundations · #reliability #design #apis
- +50 XPhardDoes This Cron Schedule Fire Now?Python Foundations · #parsing #scheduling #datetime
- +25 XPmediumJustify Text to a Fixed WidthPython Foundations · #strings #formatting #greedy
- +25 XPmediumParse a URL Query StringPython Foundations · #parsing #web #strings
- +10 XPeasyRead Nested Data with a Dotted PathPython Foundations · #dicts #json #parsing
- +25 XPmediumPriority Task Queue with CancellationPython Foundations · #heaps #design #queues
- +25 XPmediumSliding-Window Rate Limiter per UserPython Foundations · #rate-limiting #deque #design
- +10 XPeasyPalindrome PermutationsPython Foundations · #strings #counting
- +10 XPeasyRotate and Transpose a MatrixPython Foundations · #lists #matrices
- +10 XPeasyCaesar and Vigenère CiphersPython Foundations · #strings #security-basics
- +25 XPmediumBank Account LedgerPython Foundations · #classes #design #decimal
- +10 XPeasySorting by Multiple KeysPython Foundations · #sorting #lambdas
- +10 XPeasyFlatten and Unflatten Nested DictsPython Foundations · #dicts #recursion #config
- +10 XPeasyInvert a Dictionary SafelyPython Foundations · #dicts #data-structures
- +25 XPmediumA Peekable, Pushback IteratorPython Foundations · #iterators #classes #parsing
- +25 XPmediumA Mini Template EnginePython Foundations · #strings #parsing #regex
- +25 XPmediumUndo and Redo with the Command PatternPython Foundations · #design-patterns #stacks #classes
- +50 XPhardWrite a JSON Parser from ScratchPython Foundations · #parsing #recursion #strings
- +25 XPmediumBuild a Bloom FilterPython Foundations · #data-structures #hashing #probability
- +25 XPmediumValidated Attributes with DescriptorsPython Foundations · #descriptors #classes #validation
- +25 XPmediumTemporarily Patch Attributes and Dict KeysPython Foundations · #context-managers #testing #contextlib
- +50 XPhardLine-by-Line DiffPython Foundations · #strings #dynamic-programming #lcs
- +10 XPeasySliding Windows over Any IterablePython Foundations · #iterators #generators #itertools
- +10 XPeasySplit Money Without Losing CentsPython Foundations · #decimal #money #rounding
- +10 XPeasyURL Slugs from Any TextPython Foundations · #strings #unicode #web
- +10 XPeasyFormat an Aligned Text TablePython Foundations · #strings #formatting #cli
- +25 XPmediumBuild Your Own singledispatchPython Foundations · #decorators #functions #types
- +25 XPmediumParse INI Config Files with InterpolationPython Foundations · #parsing #config #recursion
- +25 XPmediumRead and Write a Binary File FormatPython Foundations · #binary #struct #serialization
- +50 XPhardConvert Markdown to HTMLPython Foundations · #parsing #regex #html
- +25 XPmediumParse CSV by Hand (RFC 4180)Python Foundations · #parsing #csv #state-machines
- +25 XPmediumDebounce and Throttle with a Fake ClockPython Foundations · #timing #closures #testing
- +50 XPhardBuild a Tiny Regex EnginePython Foundations · #regex #dynamic-programming #parsing
- +25 XPmediumDeep Diff of Nested DataPython Foundations · #recursion #dicts #testing
- +25 XPmediumFind Free Meeting SlotsPython Foundations · #intervals #time #scheduling
- +10 XPeasyNumbers to English Words and BackPython Foundations · #strings #recursion #formatting
- +25 XPmediumA Small Dependency Injection ContainerPython Foundations · #design-patterns #dependency-injection #graphs
- +10 XPeasyAn Order Lifecycle State MachinePython Foundations · #state-machines #classes #validation
- +25 XPmediumIPv4 CIDR UtilitiesPython Foundations · #networking #bits #parsing
- +10 XPeasyBusiness-Day ArithmeticPython Foundations · #dates #datetime #scheduling
- +10 XPeasyA Fixed-Size Ring BufferPython Foundations · #data-structures #classes #dunder-methods
- +50 XPhardA Trie-Based URL RouterPython Foundations · #web #tries #parsing
- +25 XPmediumTyped Config from Environment VariablesPython Foundations · #configuration #parsing #validation
- +25 XPmediumA Safe SQL Query BuilderPython Foundations · #sql #security #fluent-api
- +50 XPhardUnit Conversion with Dimensional AnalysisPython Foundations · #parsing #physics #validation
- +10 XPeasyCursor-Based PaginationPython Foundations · #apis #pagination #encoding
- +25 XPmediumA Dictionary-of-Keys Sparse MatrixPython Foundations · #data-structures #linear-algebra #dunder-methods
- +10 XPeasyImplement cached_propertyPython Foundations · #descriptors #caching #classes
- +10 XPeasySplit a List into ChunksPython Foundations · #lists #iteration
- +10 XPeasyCaesar CipherPython Foundations · #strings #encoding
- +10 XPeasyTitle Case with Small WordsPython Foundations · #strings
- +10 XPeasyInventory with Counter ArithmeticPython Foundations · #collections #dictionaries
- +10 XPeasyRemove Duplicates, Keep OrderPython Foundations · #lists #sets
- +25 XPmediumDeep Freeze for HashingPython Foundations · #immutability #recursion #hashing
- +25 XPmediumMemoise Functions with Keyword ArgumentsPython Foundations · #decorators #caching #functools
- +10 XPeasyCounting and Timing Calls with a DecoratorPython Foundations · #decorators #functools
- +10 XPeasyA Context Manager that Records Suppressed ErrorsPython Foundations · #context-managers #exceptions
- +25 XPmediumA Lazy Log-Processing PipelinePython Foundations · #generators #iteration #laziness
- +10 XPeasyCompress Numbers into RangesPython Foundations · #lists #formatting
- +10 XPeasyParse Human DurationsPython Foundations · #parsing #regex
- +10 XPeasyPassword Policy CheckerPython Foundations · #strings #validation
- +10 XPeasyLuhn Checksum for Card NumbersPython Foundations · #validation #algorithms
- +10 XPeasyValidate and Convert ISBNsPython Foundations · #validation #strings
- +25 XPmediumIBAN Validation (mod 97)Python Foundations · #validation #banking #big-integers
- +10 XPeasyDate Ranges with FiltersPython Foundations · #datetime #generators
- +25 XPmediumExact Age, Including Leap DaysPython Foundations · #datetime #edge-cases
- +25 XPmediumAuto-Registering Plugins with __init_subclass__Python Foundations · #classes #metaprogramming
- +10 XPeasyA Vector Class with Operator OverloadingPython Foundations · #classes #dunder-methods
- +25 XPmediumA Money Type with Currency SafetyPython Foundations · #classes #decimal #functools
- +25 XPmediumPermissions with enum.FlagPython Foundations · #enums #bitwise
- +50 XPhardBuilding Nested Dataclasses from JSONPython Foundations · #dataclasses #typing #parsing
- +25 XPmediumPrint a Directory TreePython Foundations · #recursion #formatting
- +10 XPeasyConverting Between camelCase and snake_casePython Foundations · #strings #regex
- +25 XPmediumA Bidirectional DictionaryPython Foundations · #dictionaries #data-structures
- +25 XPmediumA Sorted Key-Value Store with Range QueriesPython Foundations · #bisect #data-structures
- +25 XPmediumInventory Reservations with ExpiryPython Foundations · #state-management #classes #time
- +25 XPmediumA Priority Queue with Priority UpdatesPython Foundations · #heapq #data-structures
- +10 XPeasyAn Observable DictionaryPython Foundations · #dictionaries #callbacks #subclassing
- +50 XPhardApplying JSON Patch OperationsPython Foundations · #json #data-structures #parsing
- +25 XPmediumPluralising English NounsPython Foundations · #strings #rules
- +10 XPeasyDid You Mean? with difflibPython Foundations · #stdlib #strings #fuzzy-matching
- +25 XPmediumParsing a Raw HTTP RequestPython Foundations · #parsing #http #networking
- +10 XPeasyCleaning Tracking Parameters from URLsPython Foundations · #urls #stdlib
- +10 XPeasyEscaping and Unescaping HTMLPython Foundations · #security #strings
- +25 XPmediumParsing Markdown TablesPython Foundations · #parsing #markdown
- +25 XPmediumSplitting a Command Line Like a ShellPython Foundations · #parsing #state-machines
- +25 XPmediumMatching Versions Against RangesPython Foundations · #versioning #parsing
- +25 XPmediumNext Occurrences of a Recurring EventPython Foundations · #datetime #scheduling
- +10 XPeasyInvoice Totals with Decimal RoundingPython Foundations · #decimal #finance
- +10 XPeasyPagination Links with EllipsesPython Foundations · #ui-logic #lists
- +10 XPeasyRelative Time PhrasesPython Foundations · #datetime #formatting
- +10 XPeasyAggregating JSON LinesPython Foundations · #json #aggregation #files
- +25 XPmediumA Pure-Python Matrix ClassPython Foundations · #classes #linear-algebra
- +25 XPmediumA Polynomial ClassPython Foundations · #classes #dunder-methods #maths
- +25 XPmediumA Rational Number ClassPython Foundations · #classes #maths #dunder-methods
- +10 XPeasyAdding Big Numbers as StringsPython Foundations · #strings #arithmetic
- +25 XPmediumA Float Range SequencePython Foundations · #sequences #dunder-methods #numerics
- +25 XPmediumTracing Nested Calls with a DecoratorPython Foundations · #decorators #debugging #recursion
- +10 XPeasyTwo SumAlgorithms & Data Structures · #hash-map #arrays
- +25 XPmediumNumber of IslandsAlgorithms & Data Structures · #graphs #bfs #dfs
- +50 XPhardLongest Increasing SubsequenceAlgorithms & Data Structures · #dynamic-programming #binary-search
- +10 XPeasyBinary Search: First OccurrenceAlgorithms & Data Structures · #binary-search #arrays
- +25 XPmediumMerge Overlapping IntervalsAlgorithms & Data Structures · #sorting #intervals
- +25 XPmediumDijkstra's Shortest PathAlgorithms & Data Structures · #graphs #heaps
- +25 XPmediumTask Ordering with Topological SortAlgorithms & Data Structures · #graphs #dag #scheduling
- +25 XPmediumLongest Substring Without RepeatsAlgorithms & Data Structures · #sliding-window #strings #hash-map
- +25 XPmediumAutocomplete with a TrieAlgorithms & Data Structures · #trie #strings #design
- +10 XPeasyTop-k from a Stream with a HeapAlgorithms & Data Structures · #heaps #streaming
- +25 XPmediumEdit Distance (Levenshtein)Algorithms & Data Structures · #dynamic-programming #strings
- +25 XPmediumUnion-Find: Grouping DuplicatesAlgorithms & Data Structures · #graphs #union-find #dedup
- +25 XPmediumMinimum Meeting RoomsAlgorithms & Data Structures · #heaps #intervals #scheduling
- +25 XPmediumBinary Search on the Answer: Batch CapacityAlgorithms & Data Structures · #binary-search #greedy
- +50 XPhardRunning Median of a StreamAlgorithms & Data Structures · #heaps #streaming #design
- +50 XPhardA* Pathfinding on a GridAlgorithms & Data Structures · #graphs #heaps #search
- +50 XPhardConsistent Hashing RingAlgorithms & Data Structures · #distributed-systems #hashing #design
- +25 XPmediumSliding Window MaximumAlgorithms & Data Structures · #deque #sliding-window #monotonic-queue
- +25 XPmediumQuickselect: k-th Smallest in Linear TimeAlgorithms & Data Structures · #selection #partitioning #divide-and-conquer
- +10 XPeasyValid BracketsAlgorithms & Data Structures · #stacks #strings
- +10 XPeasyMaximum Subarray (Kadane's Algorithm)Algorithms & Data Structures · #dynamic-programming #arrays
- +25 XPmediumProduct of Array Except Self Daily · 2× XPAlgorithms & Data Structures · #arrays #prefix-sums
- +25 XPmediumSearch in a Rotated Sorted ArrayAlgorithms & Data Structures · #binary-search #arrays
- +25 XPmediumCoin ChangeAlgorithms & Data Structures · #dynamic-programming
- +25 XPmedium0/1 KnapsackAlgorithms & Data Structures · #dynamic-programming #optimization
- +25 XPmediumWord BreakAlgorithms & Data Structures · #dynamic-programming #strings
- +25 XPmediumLongest Common Subsequence & DiffAlgorithms & Data Structures · #dynamic-programming #strings #diff
- +25 XPmediumTwo-Colouring a Graph (Bipartite Check)Algorithms & Data Structures · #graphs #bfs
- +25 XPmediumMinimum Spanning Tree (Kruskal)Algorithms & Data Structures · #graphs #greedy #union-find
- +50 XPhardTrapping Rain WaterAlgorithms & Data Structures · #two-pointers #arrays
- +25 XPmediumReservoir SamplingAlgorithms & Data Structures · #randomized #streaming #sampling
- +50 XPhardN-QueensAlgorithms & Data Structures · #backtracking #recursion
- +10 XPeasyValidate a Sudoku BoardAlgorithms & Data Structures · #arrays #sets #validation
- +50 XPhardLFU Cache in O(1)Algorithms & Data Structures · #design #hash-maps #linked-lists
- +25 XPmediumInsert an Interval into a ScheduleAlgorithms & Data Structures · #intervals #arrays
- +25 XPmediumLongest Palindromic SubstringAlgorithms & Data Structures · #strings #two-pointers
- +50 XPhardBellman–Ford and Negative CyclesAlgorithms & Data Structures · #graphs #shortest-paths #dynamic-programming
- +25 XPmediumShortest Path in a GridAlgorithms & Data Structures · #bfs #graphs #grids
- +25 XPmediumFind the Start of a Cycle (Floyd)Algorithms & Data Structures · #two-pointers #linked-lists #cycles
- +10 XPeasySpiral Matrix TraversalAlgorithms & Data Structures · #matrices #simulation
- +10 XPeasyTop K Frequent WordsAlgorithms & Data Structures · #heaps #hashing #sorting
- +10 XPeasyBit Manipulation EssentialsAlgorithms & Data Structures · #bits #math
- +50 XPhardWord LadderAlgorithms & Data Structures · #bfs #graphs #strings
- +25 XPmediumSubsets, Permutations and CombinationsAlgorithms & Data Structures · #backtracking #recursion
- +50 XPhardMinimum Window SubstringAlgorithms & Data Structures · #sliding-window #strings #hashing
- +25 XPmediumHouse Robber (DP on a Line and a Circle)Algorithms & Data Structures · #dynamic-programming
- +25 XPmediumNext Greater Element (Monotonic Stack)Algorithms & Data Structures · #stacks #arrays
- +50 XPhardStrongly Connected ComponentsAlgorithms & Data Structures · #graphs #dfs #tarjan
- +50 XPhardSegment Tree for Range QueriesAlgorithms & Data Structures · #trees #data-structures #range-queries
- +10 XPeasyGreedy Interval SchedulingAlgorithms & Data Structures · #greedy #intervals #sorting
- +25 XPmediumKnuth–Morris–Pratt String SearchAlgorithms & Data Structures · #strings #pattern-matching
- +50 XPhardMedian of Two Sorted ArraysAlgorithms & Data Structures · #binary-search #arrays
- +25 XPmediumAll-Pairs Shortest Paths (Floyd–Warshall)Algorithms & Data Structures · #graphs #dynamic-programming #shortest-paths
- +25 XPmediumCount Inversions with Merge SortAlgorithms & Data Structures · #divide-and-conquer #sorting
- +10 XPeasyLongest Consecutive SequenceAlgorithms & Data Structures · #hashing #arrays
- +10 XPeasyPrimes: Sieve and FactorisationAlgorithms & Data Structures · #math #number-theory #sieve
- +25 XPmediumFenwick Tree (Binary Indexed Tree)Algorithms & Data Structures · #data-structures #prefix-sums #range-queries
- +50 XPhardLowest Common Ancestor with Binary LiftingAlgorithms & Data Structures · #trees #binary-lifting #graphs
- +25 XPmediumSubset Sum and Equal PartitionAlgorithms & Data Structures · #dynamic-programming #bitsets
- +50 XPhardBridges and Articulation PointsAlgorithms & Data Structures · #graphs #dfs #tarjan
- +25 XPmediumLongest Repeated Substring with Rolling HashesAlgorithms & Data Structures · #strings #hashing #binary-search
- +25 XPmedium3Sum with Two PointersAlgorithms & Data Structures · #two-pointers #sorting #arrays
- +10 XPeasyBoyer–Moore Majority VoteAlgorithms & Data Structures · #arrays #streaming #voting
- +25 XPmediumMerge k Sorted Lists and the Smallest Covering RangeAlgorithms & Data Structures · #heaps #sorting #merging
- +25 XPmediumLinear Recurrences by Matrix PowerAlgorithms & Data Structures · #math #matrices #divide-and-conquer
- +25 XPmediumStable Matching (Gale–Shapley)Algorithms & Data Structures · #matching #greedy #algorithms
- +50 XPhardMaximum Flow and Minimum CutAlgorithms & Data Structures · #graphs #network-flow #bfs
- +10 XPeasyThree-Way Partitioning (Dutch National Flag)Algorithms & Data Structures · #two-pointers #partitioning #sorting
- +25 XPmediumJump Game: Reachability and Minimum JumpsAlgorithms & Data Structures · #greedy #arrays #bfs
- +25 XPmediumWord Search in a Letter GridAlgorithms & Data Structures · #backtracking #dfs #tries
- +25 XPmediumWeighted Interval SchedulingAlgorithms & Data Structures · #dynamic-programming #binary-search #intervals
- +50 XPhardOptimal Assignment with Bitmask DPAlgorithms & Data Structures · #dynamic-programming #bitmasks #optimization
- +50 XPhardSolve the 8-Puzzle with A*Algorithms & Data Structures · #search #a-star #heuristics
- +25 XPmediumHuffman CodingAlgorithms & Data Structures · #greedy #heaps #compression
- +25 XPmediumMinimum Spanning Tree with Prim's AlgorithmAlgorithms & Data Structures · #graphs #greedy #heaps
- +25 XPmediumLongest Run After k ReplacementsAlgorithms & Data Structures · #sliding-window #strings
- +10 XPeasyMinimum Knight MovesAlgorithms & Data Structures · #bfs #grids #chess
- +10 XPeasyRadix SortAlgorithms & Data Structures · #sorting #counting-sort #integers
- +50 XPhardSuffix Array and LCP ArrayAlgorithms & Data Structures · #strings #suffix-arrays #sorting
- +10 XPeasySearch Insert PositionAlgorithms & Data Structures · #binary-search #arrays
- +10 XPeasyRemove Duplicates from a Sorted List In PlaceAlgorithms & Data Structures · #two-pointers #arrays
- +10 XPeasyMove ZeroesAlgorithms & Data Structures · #two-pointers #arrays
- +10 XPeasyRotate an Array In PlaceAlgorithms & Data Structures · #arrays #reversal
- +10 XPeasyMerge Two Sorted Arrays In PlaceAlgorithms & Data Structures · #two-pointers #sorting
- +10 XPeasyFind the Missing NumberAlgorithms & Data Structures · #bit-manipulation #math
- +50 XPhardFirst Missing PositiveAlgorithms & Data Structures · #arrays #in-place-hashing
- +25 XPmediumContainer With Most WaterAlgorithms & Data Structures · #two-pointers #greedy
- +25 XPmediumCount Subarrays Summing to kAlgorithms & Data Structures · #prefix-sums #hash-map
- +25 XPmediumLongest Subarray Within a BudgetAlgorithms & Data Structures · #sliding-window #two-pointers
- +25 XPmediumK Closest Points to the OriginAlgorithms & Data Structures · #heap #geometry
- +10 XPeasyMerge SortAlgorithms & Data Structures · #sorting #divide-and-conquer
- +25 XPmediumHeap Sort with Your Own Sift-DownAlgorithms & Data Structures · #sorting #heaps
- +10 XPeasyCounting SortAlgorithms & Data Structures · #sorting #linear-time
- +25 XPmediumIterative Tree TraversalsAlgorithms & Data Structures · #trees #stacks #traversal
- +25 XPmediumBinary Search Tree: Insert, Search, DeleteAlgorithms & Data Structures · #trees #bst
- +10 XPeasyValidate a Binary Search TreeAlgorithms & Data Structures · #trees #bst #recursion
- +10 XPeasyLevel-Order Traversal and Right Side ViewAlgorithms & Data Structures · #trees #bfs
- +10 XPeasyLowest Common Ancestor in a BSTAlgorithms & Data Structures · #trees #bst
- +50 XPhardSerialise and Deserialise a Binary TreeAlgorithms & Data Structures · #trees #design #parsing
- +25 XPmediumDiameter of a Binary TreeAlgorithms & Data Structures · #trees #dfs
- +10 XPeasyCheck if a Tree Is Height-BalancedAlgorithms & Data Structures · #trees #dfs
- +10 XPeasyReverse a Linked ListAlgorithms & Data Structures · #linked-lists #pointers
- +25 XPmediumRemove the N-th Node from the EndAlgorithms & Data Structures · #linked-lists #two-pointers
- +25 XPmediumReorder a Linked ListAlgorithms & Data Structures · #linked-lists #two-pointers
- +10 XPeasyA Stack with O(1) MinimumAlgorithms & Data Structures · #stacks #design
- +10 XPeasyA Queue from Two StacksAlgorithms & Data Structures · #stacks #queues #amortised-analysis
- +50 XPhardLargest Rectangle in a HistogramAlgorithms & Data Structures · #monotonic-stack #arrays
- +10 XPeasyEvaluate Reverse Polish NotationAlgorithms & Data Structures · #stacks #parsing
- +25 XPmediumDecode a Nested Repeat StringAlgorithms & Data Structures · #stacks #parsing #recursion
- +25 XPmediumGenerate Balanced ParenthesesAlgorithms & Data Structures · #backtracking #recursion
- +25 XPmediumCombination SumAlgorithms & Data Structures · #backtracking
- +10 XPeasyLetter Combinations of a Phone NumberAlgorithms & Data Structures · #backtracking #strings
- +25 XPmediumPalindrome PartitioningAlgorithms & Data Structures · #backtracking #dynamic-programming #strings
- +25 XPmediumUnique PermutationsAlgorithms & Data Structures · #backtracking #combinatorics
- +10 XPeasyMinimum Cost Climbing StairsAlgorithms & Data Structures · #dynamic-programming
- +25 XPmediumUnique Grid Paths with ObstaclesAlgorithms & Data Structures · #dynamic-programming #grids
- +25 XPmediumLongest Palindromic SubsequenceAlgorithms & Data Structures · #dynamic-programming #strings
- +50 XPhardMatrix Chain Multiplication OrderAlgorithms & Data Structures · #dynamic-programming #interval-dp
- +25 XPmediumRod CuttingAlgorithms & Data Structures · #dynamic-programming #optimization
- +50 XPhardThe Egg Drop ProblemAlgorithms & Data Structures · #dynamic-programming #puzzles
- +50 XPhardInterleaving StringsAlgorithms & Data Structures · #dynamic-programming #strings
- +50 XPhardWildcard Pattern MatchingAlgorithms & Data Structures · #dynamic-programming #strings #greedy
- +25 XPmediumMulti-Source BFS: Rotting OrangesAlgorithms & Data Structures · #bfs #grids
- +25 XPmediumCheapest Flight with at Most K StopsAlgorithms & Data Structures · #graphs #bellman-ford #shortest-paths
- +50 XPhardReconstructing an Itinerary (Eulerian Path)Algorithms & Data Structures · #graphs #eulerian-path #hierholzer
- +10 XPeasyFlood FillAlgorithms & Data Structures · #dfs #grids
- +25 XPmediumExtended Euclid and Modular InversesAlgorithms & Data Structures · #number-theory #math
- +10 XPeasyFast Modular ExponentiationAlgorithms & Data Structures · #number-theory #divide-and-conquer
- +25 XPmediumRabin-Karp Rolling Hash SearchAlgorithms & Data Structures · #strings #hashing